#include <iostream>
#include <iomanip>
using namespace std;
int main()
{
   int n;
   cin >> n;
    int sum = 0;
   while(n>0)
   {
       int temp = n%10;
       sum = sum + temp;
       //cout << temp;
       n = n / 10;
   }
    cout << sum;
    
}